Solve the Equation by Factoring $$- 6 x - 2 = ( 3 x + 1 ) ^ { 2 }$$

Multiple Choice

Solve the equation by factoring.
- $$- 6 x - 2 = ( 3 x + 1 ) ^ { 2 }$$

A) $\varnothing$
B) $\left\{ - 1 , - \frac { 1 } { 3 } \right\}$
C) $\left\{ - \frac { 1 } { 3 } \right\}$
D) $\left\{ \frac { 1 } { 3 } , 1 \right\}$